Chain stitch sewing machine



Jan. 22, 1935. M. M CANN I CHAIN STITCH SEWING MACHINE Original Filed July 26, 1930 2 Sheets-Sheet l Jan. 22, 1935. MocANN CHAIN STITCH SEWING MACHINE Original Filed July 26, 1950 2 Sheets-Sheet 2 out from my application Serial No; 470,861

July.26, 1930-for Sewing machines;

Patented jan. 22 1935 a *1,9ss;"o 2' CHAIN STITCH SEWING MACHINE Michael Mecann, St. Albans,i;L ongIsIan d,,N. Y.,

. assignorgby mes ne assignments, to The Singer 7 Manufacturing Company, Elizabethport; N. J.,

a corporation of New Jersey Original application. July-26, i930. ear No. I a 470,861. Divided and this-application February v .6,1932,SeriaI No.591,254'i J This invention relates to sewingfmaehines more particularly to singlethread or chain stitch machines, and has-for its object to improve the control of the thread so as to prevent.the;forma- .tion; of loose loops of thread in the finished {work i as frequently happens with this type oi machine when used. for sewinggombuttonsor wnapping wire or other strand materials or fabrics.

To this end a thread tension is interposed between the needle and the take-up which, however, is released at certain times. such release is desirable particularly at the starting of a sewing operation to prevent the starting end of the: thread from being drawn back out of the needle eye; and at the end of the cycle to permit the threadtto be drawn forwardly through the needleeye to leave sufficient length of thread} extending therethrough for the start of a succeeding sewing operation. r g

This application covers subject matter divided Referring to the accompanying drawings; p Figure 1 is: a side elevation partly broken away of a sewing machine embodying this invention. Figure 2 is a horizontal section on line 2-2 of Figurel.

' Figure 3,is a front end elevation ot-the machine in position to start the stitching cyclei Figure dis a View to a larger scale similar to a portion of Figure 2 and showing the thread tension in operative condition.

Figure 5 is a detail section on line 55 of Figure 3 but showingthe tensionreleased. i

Figure 6 is a detailsection on'line 66 of Figure 5 l e I Figure 7 is a fragmentary perspective 'of the tension and release mechanism.

Figure 8 is a detail section on line 8-8 of Figure 1.

Referring to the drawings,'at, 1 is shown the base of a sewing machine of a well known type for securing buttons with a single thread chain stitch, having a post 2 upstanding from its re'ar end merging with a forwardly extending arm 3 having a sewing head 4'at its forward end. 'At 5 is indicated a needle bar tothe lower end of and by;thema ;in shaft 10 by any suitable asjswell knownin the art.

- insul s. (or. 112-255) through whichthe needle bar isislidably mounted; The rearend-of the lever is provided with a cam follower liriding in a cam groove 18 (see Fi ure 2) in a; cam 19.1'1xed to; a vertical shaft 20.

Beneath the needle bar the base 1 is provided witha =Werktabla25 beneath which is positioned a looper such as 26 carried by a looper shaft 2'1. The looperi-s drivenin suitable timed relation to means Beneath the arm 2 is-positioned a work holder shown generally at 30. ,Thiswork holder as shown is formed tog engage wireswhich it is desired towrap with thread but it might; be a button clam-p or other device if desired. A carrier bar 33 to theforwardend of which the work holder is secured is hinged on a horizontal pintle 47 at its rear endso that theholder mayberaised from the work table. It; isnormally. held pressed. to- Ward the work table asby a spring pressed plunger 56 in a well known manner. It may be raised from the: work to: breakthe thread after the last stitch of a sewing operationtorelease the work as by the rocking of a rock-shaft 70 (see Figure 3 to which is fixed an arm" 7Ilconnected to the Work holder :as by means of. a chain 72. arm '75 fixedto' the rock-shaft maycbe connected to an actuating means "such; as a treadle :(not shown) through a link 74.: To theforward endof the rock shaft 'llimay be secured: an arm 131i providedwith athread retainer 130 for engaging the p starting thread end prior to a stitching operation and holding it until the needle has engaged the thread withtthe work, whereupon thethread: end isi pulledl out from. the retainer as is' more fully shown and claimed inmy application for patent Serial No. 591253111166. February 6, 1 93 2 for Sew,

ing machine.

In order to' prevent the formation of loose loops of thread, tension isapplied, accordingv to: this invention-tothe thread in the lead of. the thread between theneedle: and the take-up; .It is found that ,the descent of the needle from the beginning of its stroke has a tendency to bulge and pile up the thread between the needle eye and the work with the result that this bulge isoften pierced by the needle point causing aloose stitch or damaged thread, or both. H Bypositioning a stationary thread tension which thus does not move with the needle between the. needle and thetake-up,

the threadi'sheld tension-tight between the takeup aridthe work, allowing the needle eye. to slide downthe thread to the-f work" without the possibility of bulging'the thread? I-tis not desirableto apply this tension during the formation of the 5 thread end may be insufliciently securely caught.

At 190 in Figure3 is shown-a usual form of take-up mounted on the needle bar and from this, the thread as 191 passes downward through the tension 192 to the eye 7 of the needle. best in Figures 4, 5, and 6 this tension may comprise a bar 95 fixed as at. 96 as by screws to the forward face of the sewing head 4 and having spring pressed against its forward face an element 97 which may be of sheet materialhaving opposite edges flanged over as at 98 (see Figure '7) to engage opposite sides of the bar 95. At 99' may, be placed notches in these flanges to form a This element 97 may be pressed thread guide. against the forward face of the bar 95 and for this purpose there is shown a screw 100 extending through the element 97 and threaded into the bar 95 and surrounded by a coil spring101. For the purpose of adjustment this screw 100 is shown as positioned within an opening 102 through the front face of the head 4 so that it may beacces- 'sible to a screw driver for adjusting the extent of its engagementin the bar 95 and thus the pressure of'the spring 101 on the element 97.

' For the purpose of releasing the tension automatically during the first few stitchesuntil the starting thread end is sufiiciently secured and at the endof the stitching cycle the following means may be provided. Fixed as by a screw 105 to the rear face of the bar 95 is a cam element 106 having an inclined cam face 107 and at its'free' end a forwardly extending portion 108 projecting through an opening through the bar95andinto engagement with the rear face of the tension element 9'7" This member 106 may be formed of sheet material and the portion 108 thereof may be formed by cutting and striking forwardly a portion thereof. By springing this cam member forwardly it is evident that the element 9'7 will be pressed away from the bar 95, thus relieving the tension on the thread. This may be done by means of an arm. 110 fixed to a rockshaft :111 journaled in the upper portion of'the arm 3 and having at its rear 'enda camarm 112-which may be engaged air-the beginning and end of the stitching operation by a cam projection 113 on the'top. face of the cam 19. The rock shaft 111 is normally held in such angular position that tension-isresumed. The free end of the tensionelement 97is preferably bent forwardly as at 120 to facilitate placing the thread in position between it and the .bar 95. From the foregoing description of an embodiment. of this. invention it shouldbe evident to those skilled in the art that various changes and modifications. might be made without departing "from: the spirit or scope of this invention as defined'by the appended claims- As shown When the stitch- 1. In a sewing machine, sewing instrumentalities including a needle and a take-up, a thread tension between said needle and take-up and with respect to which said needle moves, and means automatically releasing said tension during a predetermined portion of the stitching operation.

2. In a sewing machine, sewing instrumentalities including a needle and a take-up, a thread tensionnbetween said needle and take-up and with respect. to which said needle moves, and means automatically releasing said tension during a predetermined initial portion of the stitchin operatio 3. In a sewing machine, sewing instrumentalities including aneedle and a take-up, a thread tension between said needle and take-up and with respect *td'which said needle moves, and means automatically releasing said tension during the formation of the first few stitches of a stitching operation. 1' f I 4. In a sewing machine, sewing instrumentalities including a needle and a take-up, a thread tension between said needle andtake-up, means including a'cam for vibratingsaid needlelaterally between successivestitches, and means including an element of said cam for releasing said thread tension duringapredetermined number of stitches. v

5. A thread tension comprising a bar, an element spring-pressed toward'one'face of said bar togrip a thread therebetween, and a cam mem ber onthe opposite face of said bar having a portion extended through an opening through said-bar into engagement with said element and a'ctuable to press said element away from said bar to release thethread. v v

6. In a sewing machine, sewing instrumentalities including a needle and a take-up, a threadtension between said needle and take-up,

means for grasping the thread end at thestart ties including a needle and av take-up, a stationary thread tensionbetween the needle and the take-up in the lead of the thread holding the thread'under tension during a needle stroke between the take-up and the work whereby the needle eye may slide along the thread to the work without bulging the thread, and automatic,means causing saidtension to be inoperative at predetermined times. l

9. In a sewing-machine, sewing instrumentalities including a needle and a take-up, a

stationary threadtension between the needle andthe take-up in the lead of the thread holding the thread under tension during a needle stroke between the take-up and the work whereby the needle eye may slide along the thread to the work without bulging the thread, and automatic means causing said tension to be inoperative at the end of and atthe start of machine operation. a

- MICHAEL McCANN. 

